Towbar apparatus

ABSTRACT

An apparatus for towing large vehicles, such as aircraft, and comprising an elongated braking drum, braking means offering frictional resistance to translation of and mounted about such drum and a recirculating ball bearing assembly disposed within and secured to the drum providing for the additional bearing surfaces required under an overload condition for or on the towed device. The assembly is mounted on a screw member fixed to the towing end of the apparatus. The drum is connected at its towed end to a radial-and-thrust bearing coupling while the braking means is supported and fixed at a given position by a tube connecting the apparatus at its towing end to a latching mechanism. An axial load applied through the apparatus is absorbed by the frictional resistance provided between the braking means and drum. When a predetermined frictional value is exceeded, the apparatus begins to telescope, by reason of the drum rotating upon the screw member. This may provide for a signal to the operator that an overload on the towed device has occurred. The overload energy of the apparatus, nevertheless, is absorbed by heat generated between the braking means and the drum as the latter rotates, without making inoperative or damaging the apparatus, or disconnecting it from the towed device. The towbar may then be reset for continued operation.

United States Patent 1191 Olson 1451 Jan. 9, 1973 [54] TOWBAR APPARATUS[57] ABSTRACT Inventor: David 0|80l1,Bul'bank,C8|if- An apparatus fortowing large vehicles, such as air- [73] Assignee: Lockheed AircraftCorporation, and comprising .elongatefj braking drum Burbank Calm brakmgmeans offering frlctlonal resistance to translation of and mounted aboutsuch drum and a recircu- Filedi g- 1971 lating ball bearing assemblydisposed within and secured to the drum providing for the additionalbear- [21] Appl' 175666 ing surfaces required under an overloadcondition for or on the towed device. The assembly is mounted on a [52]U.S.Cl ..280/453, 180/14 C, 188/129, screw member fixed to the towingend of the ap- 280/475, 280/476, 280/507 paratus. The drum is connectedat its towed end to a [51] lnt.Cl. ..B60d 3/00 radial-and-thrust bearingcoupling while the braking [5 8] Field of Search.....280/453, 446, 449;180/14 C; means is supported and fixed at a given position by a 188/129;267/9 C, 10; 254/86 R tube connecting the apparatus at its towing end toa latching mechanism. An axial load applied through the References Citedapparatus is absorbed by the frictional resistance provided between thebraking means and drum. When a UNITED STATES PATENTS predeterminedfrictional value is exceeded, the ap- 2,541,356 2/1913 Hansmann..280/452 begins telesmpe, by "9" the i 2,856,179 10/1914 Hogan t ..1ss129 mating upon the Screw member- Thls may Provide for 3,059,727 10/1923Fuchs ..1ss/129 a Signal to the Operator that an Overload on the towed3,300,233 1 1924 Olson ..280/453 device has urred. The overload energyof the ap- Primary Examiner-Leo Friaglia Assistant Examiner-Vincent HomAttorney-Frank L. Zugelter et a1.

paratus, nevertheless, is absorbed by heat generated between the brakingmeans and the drum as the latter rotates, without making inoperative ordamaging the apparatus, or disconnecting it from the towed device. Thetowbar may then be reset for continued operation.

8 Claims, 5 Drawing Figures PATENTEDJMI 9mm 3,709.522

sum 1 0F 3 IINVENTOR. DAVID C. OLSON Agent PATENTEDJAI 9 I973 snmanraFIG. 5

FIG. 4

INVENTORQ DAVID c; OLSON Agent TOWBAR APPARATUS BACKGROUND OF THEINVENTION 1. Field of the Invention The field of art to which theinvention is most likely to pertain is located in a class of devicesgenerally relating to towing devices. Classes 92, Expansible ChamberDevices; 188, Brakes; 192, Clutches and Power-Stop Control; and 280,Land Vehicles, U.S. Patent Office Classifications, may be the applicablegeneral areas of art in which the claimed subject matter of the typeinvolved here may be classified.

2. Description of the Prior Art An example of a prior art device in theart or arts to which this invention most likely pertains is U.S. Pat.No. 2,541,356.

PROBLEMS IN THE PRIOR ART AND INDUSTRY Movement of huge jet aircraftdemands considerable efforts of man and machine, and such efforts havebeen found to include the necessity of coordination for such movementbetween the vehicles pilot and ground personnel together with use ofprime movers, towbars and other equipment for safely rolling suchvehicles from and into one position to or from another.

The advent of huge aircraft has also created problems concerning theirmovement about and around cargo and passenger terminals; i.e., in areaswhere very slow movement is required and other than 'in the taxiing andflying runways. Initially, the aircraft must overcome its own inertia byconsiderable power. One known method to do this is by revving up itsengines. However, fuel economy is not realized, also, danger exists tothe welfare of ground personnel and others in the area from the engineblasts and turning movements of the aircraft. Further, limited visionthrough the cockpit window by a pilot clearly exemplifies the fact thatmaneuverability with complete visual observation of all features of theplane is impossible.

Consequently, equipment such as prime movers and towbars have beenutilized for some time now, to move such aircraft in an easy, safe andhandily manner, with the results of aircraft fuel economy and safety andhealth of persons in the immediate vicinity of the moving aircraft.

Large or heavy aircraft now in existence and still being developedrequire not only a prime mover and towbar arrangement, but also a movingsystem which includes load limiting protection to the vehicle or tolanding gear to which the towbar is latched. In other words, withoutsome check on how much load the vehicle or landing gear can take, itsconnected towing device could severely damage the vehicle and suchlanding gear by pulling such vehicle or gear, or such accessory thereto,beyond its elastic load limits. In the past, shear pins or solidconstructions in towbars have been utilized in a purposeful manner tofail, rather than have damage result to a landing gear and towed planethemselves. However, various problems resulted in broken towbars andadditional time for moving a jet aircraft accompanied such a use.

SUMMARY OF THE INVENTION An object of this invention, then, is toprovide a towing system including load limiting features which maysignal an operator that an overload has been imposed upon a landinggear.

Another object of this invention is to provide a selected load for atowbar apparatus which is safely below the design limits of an aircraftlanding gear or other device to-be-towed, whereby the apparatus need notbe disconnected from the towed device, or made inoperative or damagedotherwise, but only stopped and reset upon the occurrence of such anoverload.

Another object of the invention is the provision of a variable loadlimiting capacity in a towbar apparatus.

A further object of this invention is the provision of anenergy-absorption feature in a towbar'and which otherwise would berequired to beplaced directly into a vehicle or landing gear.

Other objects of this invention are to provide a novel towing apparatusand an improvement therein.

These and other objects and inventions will become apparent upon a fullreading of the following description, appended claims thereto, and theaccompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a side elevational view of anembodiment of my invention in an actual position for towing.

FIG. 2 is a view taken on line 2-2 ofFIG. l.

FIG. v3 is a view, partly in section and partly broken away, of aportion of the embodied towbar shown in FIG. 1.

FIG. 4 is a view taken on line 44 of FIG. 3.

FIG. 5 is a fragmentary view, partly in section and partly broken away,of the latching end for the towbar embodiment shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing inwhich reference characters correspond to like numerals in the followingdescription, reference character 10 refers in general to A a towbarapparatus embodying my invention. Towbar 10 is illustrated in FIG. 1 tobe in an exemplary position for use, say, between a frontal landing gear12 ofa huge or very heavy jet aircraft (not shown) and a strongbifurcated member 14 securely mounted on a prime mover or vehicle 15 formoving such a heavy vehicle.

Towbar 10 comprises an elongated brake drum 18 (FIG. 3) about which oneor more braking means 20 offering frictional resistance to rotationthereof is mounted for cooperative action therewith, a recirculatingball bearing assembly 22 disposed within and secured to drum I8, and aconventional housed thrustand-radial bearing coupling 24 secured to theone end of drum l8. Coupling 24 transmits loads through itself andprovides rotational ability for the drum l8. Coupling 24 is suitablyconnected to a means 25, such as a lunette eye, provided for connectingthe one end of towbar 10 to bifurcated member 14 by means of a pin 26. Ameans 27, such as atube 28 and a finger means 29 longitudinally securedto one end of tube 28, is prov 30 suitably mounted on and suitablysecured to the interior end of tube 28 is centered about drum 18 bymeans of its connection to braking means 20 through finger means 29. Acollar spacer 31 is threaded to the other end of drum 18 andslip-fittedly engages the interior wall of tube 28. Annular flange 30preferably terminates immediately adjacent the braking means 20, andwhich means 20 is shown in FIG. 3 to be in a nominal position for towbar10.

The nominal position (FIG. 3) for towbar may be defined as the relativepositions of the drum l8 and braking means prior to application totowbar 10 of a predetermined loadvalue at which drum 18 would begin torotate and to axially translate or move against the frictionalresistance provided by braking means 20. Means 20 is conveniently heldat its nominal position on brake drum 18 by means of one or more of thefinger means 29 mounted on a longitudinally extending bracket 32suitably secured to flange as shown in FIG. 4. Spaced lugs 33 aresuitably provided on the periphery of each braking means 20 and by whicha finger of means 29 captures means 20. The lugs 33 are configurated andarranged in relation to drum 18 such that braking means 20 cannot rotateabout it.

Each braking means 20 comprises (FIG. 4) a frictional lining 35 bandedabout brake drum 18 and held thereabouts by means of an adjustabletension means 36 which produces such predetermined load value byproviding a desired degree of frictional engagement between lining 35and drum l8. Tension means 36 comprises a pair of spaced bracket memberseach havingan upright portion 39 and a portion 40 secured, such as byrivets, to lining 35 adjacent its ends 42, and a biasing bolt-and-nutarrangement 44 capable of drawing together the upright portions 39.Adjustment by which the desired degree of frictional engagement isobtained is provided for by a spring 45 coiled about the bolt betweenone upright portion 39 and its nut, whereby adjustment of the nutposition on the bolt adjusts the tension in the lining 35 and,consequently, the degree of such frictional engagement. Access for suchadjustment is made convenient through a door 46 provided in a protectivehousing 47 suitably mounted about coupling 24 and extending to andcircumscribing a suitable length of tube 28. Plate covers 48 ensuretotal easement of coupling 28 and braking means 20.

Release of lining 35 from drum 18 is provided by a rotatable cam head 49disposed between the spaced upright portions 39. Rotation of cam head 49into engagement with the one portion 39 causes the latter to reactagainst spring 45 and thus provide for such release. An operating shaft50 is provided for cam head 49 and is conveniently supported in flange30 and in a flat bracket member 51 circularly mounted adjacent the outerend 52 of tube 28, and through which member 51 outer end 52 projects. Asuitable hand crank 53 is attached to such end of shaft 50 for ease ofreleasing and engaging braking means 20 about drum 18.

It may be noted from FIGS. 3 and 4 that a second braking mechanism 54and its attendant features such as described immediately above areincluded in the preferred embodiment. By this additional mechanism 54,towbar 10 is applicable throughout a greater range of loads, and thus tolarger sized of vehicles (aircraft,

by way of example), than were merely one braking means 20 included intowbar 10. In effect then, two or more braking mechanisms 20, 54, etc.,provide a towbar device 10 with the capability of moving vehicles havinga very wide variety of mass; For the greater loads, more than onebraking means 20, 54, etc. would be engaged by rotating their respectivecam heads 49 out of contact with their respective uprights 39. Acorresponding plurality of finger means 29, of course, would then alsobe utilized.

At the end 52 ofsupport tube 28, a means 56, such as suitable threadingand pinning elements, is provided for securing the one end of a screwmember 57 forming a portion of assembly 22, and thereby eliminaterotational movement for screw member 57 relative to support tube 28. Amating nut 58 for and mounted on screw member 57 provides for retentionof a plurality of complement of freely movable bearing balls 59 inhelical races 60 formed in screw member 57 and its mating nut 58. Anannular ring nut 61 is threadedly mounted to the one end of mating nut58 and means such as a pin 62 secures assembly 22 to drum 18.

Assembly 22 and screw member 57 together is a commercially availableitem. An example thereof, one which is satisfactory for the operation oftowbar 10, is what is known in the trade as a recirculating ball screwjack, or Saginaw bearing ball (b/b) screw made and sold by the SaginawStearing Gear Division, General Motors Corporation, Saginaw, Mich. Itshould be noted that FIG. 3 does not disclose certain details of such aSaginaw b/b screw with regard to the recirculation of the bearing balls59; however, such details are well known in the trade as same is partand parcel of such a commercial product. Such recirculation provides forthe continual bearing between screw member 57 and drum 18 required inthe operation of towbar 10, particularly in regard to the relativeextension and retraction of drum 18 to tube 28.

The end 52 of tube 28 supports a solid body 64 having a flange 65secured to end 52 and an extension 66 adapted to connect to and supporta latching mechanism 70 for towbar l0. Latching mechanism 70 (FIGS. 1and 5) is provided for connecting landing gear 12 to towbar 10. Itshould be understood that mechanism 70 is not part of the essence of theinvention, and is illustrated merely for the purpose of assistingunderstanding of this disclosure, by showing in one instance how towingdevice 10 is capable of actually being used. In this instance, asapplied toan aircraft landing gear. Other latching mechanisms and fieldsof use for apparatus 10 are-equally available for use with my invention.

Latch mechanism 70 (FIGS. 1, 2, 5) comprises a pair of verticallydisposed bifurcated jaws 72 extending forwardly from a pair ofhorizontally disposed bifurcated arms 74, and are suitably secured, suchas by welding, to the latter. Arms 74 are pinned as at 76 to the solidextension 66 of solid body 64. A latching means 82 is pivotallyconnected as at 84 to and is disposed between bifurcated jaws 72 andcomprises a hand 86 closable upon a tow-pin 88 of the landing gear 12(FIGS. 1 and 5). Hand 86 includes a bifurcation into which an adjustablethreaded rod 90, having an eyelet 91 at its one end, is introduced andpivotally connected to hand 86 by means of a cross-rod 92. The other endof rod 90 passes through a bar 94 suitably held in place between a pairof spaced bracket members 96 pivoted to jaws 72, as at 97, and to whicha handle 98 is attached. The length of rod 90 is adjustable at bar 94 byhex nuts 100 mounted to each side of bar 94. As handle 98 is rotatedclockwise fashion, the action of rod 90 pivots hand 86 into an openposition for introduction or removal of tow-pin 88. Counter-clockwiserotation of handle 98 provides action for rod 90 such that hand 86clamps upon tow-pin 88.

It may be noted that the adjustability of the longitudinal position foreyelet 91, provided by adjustment of rod 90 at bar 94, provides suitableclamping upon various sized tow-pins 88 or other element upon whichlatching means 70 may easily seize.

A pair of spaced fingers 102 projecting forwardly and overly of jaws 72,and to each side of latch hand 86, is suitably secured to suchbifurcated jaws 72, for

resting upon a tow-pin 88 or the like in the event that a wheelingapparatus 110 (FIGS. 1, 2) is in a raised position and hand 86 is in anopen position, in order to prevent dropping of the one end of towbarapparatus with its other end is hooked to the prime mover 15.

Towbar 10 is provided with a wheeling apparatus 110 by which it istransportable along the ground, either by prime mover or by manualmanipulation, prior to connecting it to, say, landing gear 12. Wheelingapparatus 110 comprises a conventional tire-and-axle combination 112 andan undercarriage frame 116 suitably mounted thereto, all of which may befabricated in a conventional manner. Frame 116 is pivotally connected,as at 118, to housing 47. A conventional mechanical jacking device 120(FIG. 1) is pivotally connected to both housing 47 and frame 116, as at122, 124, respectively, for raising wheeling apparatus 110 up off ofground surface after towbar 10 has been positioned, as shown in phantomin FIG. 1, and during towing of tow-pin 88 and its vehicle. Forstationarily positioning towbar 10, a suitable skid arrangement 126 maybe provided.

In operation, apparatus 10, held in its nominal position by means of atleast one of the braking means 20, 54 engaging drum 18, and with itswheeling apparatus 110 in down or rolling position, is rolled to andconnected to tow-pin 88. Thereafter, the jacking device 120 is operatedto raise the other end of apparatus 10 to a level at which lunette eye25 is connected to prime mover l5. Thereafter, mechanicaljack 120 isoperated to raise wheeling apparatus 110 out of ground surface contact.Apparatus 10 is now supported solely by prime mover l5 and landing geartow-pin 88, and prime mover 15 is in position to pull or push thevehicle on which tow-pin 38 is mounted by means of tow-bar 10.

One or more of the braking means 20, 54 has been applied to brake drum18 by actuation of its or their corresponding cam means 49 through theoperating shaft 50 and hand crank 53. Prime mover l5 begins to pull orpush. Under axial load conditions, up to a predetermined value, thefrictional application of brake means 20 and/or 54 to brake drum l8prevents rotational movement of drum 18 relative to tube 28, as suchaxial load is transmitted from the landing gear 12 through tube 28,braking means 20, drum 18, coupling means 24, and finally to prime mover15. Should the pre-set frictional value of such axial load be exceeded,

then drum l8 begins to rotate and axially translate or move against thegrip of braking means 20 and/or 54, as prime mover 15 pulls or pushestowbar 10.

As an axial load is initially applied, the load at the one end of towbar10 is carried from the lunette eye 25 through coupling 24, drum 18, andthen to the recirculating ball bearing assembly 22. A reaction to suchload is developed in or by screw 57 connected through fixed end 52 tothe solid body 64, its extension 66 and latching means 70. As the loadvalue increases to over its predetermined frictional value, the matingnut 58 tends to rotate, drum 18 rotating with it. In other words, theturning moment on drum 18 overcomes the frictional resistance providedby braking means 20. Drum 18 and mating nut 58 move to the left in FIG.3 as prime mover l5 pulls, and they move to the right as prime mover l5pushes, while bearing balls 59 correspondingly recirculate to activeraceways along the length of assembly 22 to maintain the continualbearing required for towbar 10 to undertake such an excessive load. Inother words, drum 18 is capable of rotating in relation to screw 57because of the radial bearing function of coupling 24. As lunette eye 25is connected to prime mover 15 and carries its load into drum 18 throughcoupling 24, it remains in a static condition even through drum 18 mayrotate.

In order to control the load at which drum l8 begins to rotate, and movefrom its nominal position, braking means 20 and/or 54 bear frictionallyupon it. These braking means are, of course, individually adjustable tovary the load limiting point or value at which drum 18 begins to rotate.The constant friction occuring therebetween after the load limitingpoint has been exceeded provides a constant load resistance, as drum 18is pushed or pulled while it resistingly rotates and slides through thebraking means 20 and along a ground surface (FIG. 3) of constantdiameter of drum 18.

Should the relative travel between drum 18 and braking means 20 exceedthe distance provided along the constant diameter of ground surface 130on drum 18, so that means 20 reaches an unground or divergingly taperedsurface 132 provided on each end of drum 18, such friction thenincreases, and rises on a graduated scale depending on the degree of thediverging taper between the ground to unground surfaces. The load limitfor towbar 10, therefore, is increased by such taper. These tapers 132also constitute means for stopping rotation of drum 18 before mating nut58 disengages from screw 57 in the one instance of prime mover 15pulling towbar 10, or before the collar spacer 3] contacts the fittingor means 56 in the other extreme instance in which a prime mover l5'ispushing a towbar against tow-pin 88. A suitably-sized opening 133 isprovided in annular flange 30 for passage of the tapered surfaces 132adjacent the collar spacer 31 in the event of an extreme telescoping oftube 28 relative to drum 18.

An auxiliary tube 134, with suitable mounting flanges 136, may besuitably fixed to and confined Within drum 18 to provide for additionalcentral alignment and support for screw 57. This also assists inmaintaining a proper spacing for tube 28 about drum 18, as alignment ofscrew 57 carries with it a centering for tube 28 to which it is attachedat its end 52.

It should now be apparent that assembly 22 and coupling 24 providerotational capability to drum 18, while assembly 22, drum l8 and brakingmeans 20 absorb an axial load between the prime mover l and the vehicle.

To return or retract towbar 10 to its nominal position after atelescoping extension between drum l8 and tube 28 has occured, allbraking means 20, 54, etc., are first released from their frictionalengagement with drum 18. Then, say, with the use ofa prime mover l5, andwhile latching mechanism 70 is still clamped to a tow-pin 88 of anaircraft which is stationarily held, housing 47 is telescoped upon tube28. Drum 18 readily rotates about assembly 22. Upon reaching nominalposition, one or more of the braking means 20 may then be re-engaged. Asuitable marking or other device may be mounted on the exterior oftowbar 10 to inform the operator what the relative positions of tube 28and housing 47 are, in the nominal position for towbar 10.

Visual means, not a part of this invention, may be added to the exteriorof apparatus 10 in a suitable manner in order to inform the operatorthat it is no longer in its nominal position.

It should now be apparent that the telescoping effect of towbar 10, ineither extending or retracting mode, as it undertakes loads exceeding apredetermined frictional value, may provide a signal to the operatorthat an overload condition exists relative to the towbar. Thesignificance of this is not so much directed to maintaining anoperational condition for towbar 10 itself as it is in relation to thestrength of a vehicle landing gear. In other words, all loads undertakenby towbar 10 can be correlated to a known strength ofa vehicle or atow-pin in a landing gear during the design stages of the particularvehicle or aircraft involved.

It should also be apparent that the overload energy of towbar I0 isabsorbed by heat generated between the braking means and the drum as thelatter rotates.

Pursuant to the requirements of the patent statutes, the principle ofthis invention has been explained and exemplified in a manner so that itcan be readily practiced by those skilled in the art to which itpertains, or with which it is most nearly connected, suchexemplification including what is presently considered to represent thebest embodiment of the invention. However, it should be clearlyunderstood that the above description and illustrations are not intendedto unduly limit the scope of the appended claims, but that therefrom theinvention may be practiced otherwise than as specifically described andexemplified herein, by those skilled in the art, and having the benefitof this disclosure.

Therefore, what I claim as patentably novel is:

I. In an apparatus for towing and having first and 6. a screw memberbeing fixed to the first end of said apparatus, said assembly and drumbeing capable of rotating and translating thereon, and

. means for frictionally engaging and releasing said braking means toand from said drum, whereby as an axial load is imposed on saidapparatus, it is transmitted to said braking means, drum and assembly,the energy of any load thereon in recess of a predetermined frictionalvalue, at which value said assembly and drum rotate and translate onesaid screw member, being absorbed by heat generated between said brakingmeans and drum as the apparatus telescopes, without separation of ordamage or inoperativeness to said apparatus occuring.

2. In the apparatus of claim I, the addition of means for adjusting thetension of said braking means about said drum.

3. In the apparatus of claim 2 including means for stopping rotation ofsaid drum after said apparatus has telescoped.

4. In the apparatus of claim 3, said stopping means comprising at leastone diverging tapered surface mounted on said drum, said divergingtapered surface cooperating with said braking means to stop rotation ofsaid drum.

5. An apparatus for towing comprising in combination,

1. two ends for said apparatus,

2. an elongated drum member,

3. braking means offering frictional resistance to and mounted aboutsaid drum member,

. means for supporting said braking means about said drum and beingsecured to one of such ends of said apparatus,

5. a radial-and-thrust bearing coupling disposed at and secured to theother of such ends of said apparatus, said drum being operativelyconnected thereto,

6. a recirculating ball bearing assembly disposed within and secured tosaid drum,

7. a screw member being fixed to one of such ends of said apparatus,said assembly and drum being capable of rotating and translatingthereon, and

8. means for frictionally engaging and releasing said braking means toand from said drum, whereby as an axial load is imposed on saidapparatus, it is transmitted to said braking means, drum and assembly,the energy of any load thereon in excess of a predetermined frictionalvalue, at which value said assembly and drum rotate and translate onsaid screw member, being absorbed by heat generated between said brakingmeans and drum as the apparatus telescopes, without separation of ordamage or inoperativeness to said apparatus occuring.

6. The apparatus of claim 5 including means for adjusting the tension ofsaid braking means about said drum. 7

7. The apparatus of claim 6 including means for stopping rotation ofsaid drum after said apparatus has telescoped.

8. The apparatus of claim 7 in which said stopping means comprises atleast one diverging tapered surface mounted on said drum, said divergingtapered surface cooperating with said braking means to stop rotation ofsaid drum.

UN ETED STATES PATEN mam-0E I QERTEFEQATE @F QQRREQTEN.

Patent No. 3,7C9;522 Dated Januafv 9, 1973 Inventofls) DAVID C, OLSON Itis certified that error appears in the above-identified patent and thatsaid. Letters Patent are hereby corrected as shown below:

in Qolm 8; line 8 "recess" should read ---excess In colmn 8, line 10,'one shduld read --0n--- Signed 5nd sealed this 29th day of May 1973.

(SEAL) Attest:

EDWARD M.-FLETCHER,JR. e ROBERT GOTTSCHALK Attesting OfficerCommissioner of Patents OHM PO-1050 (10-69) USCOMM-DC 60376-P89 i U. 5.GOVERNMENT PRINTING OFFICE I96! O-366-33l

1. In an apparatus for towing and having first and second ends, theimprovement comprising,
 1. an elongated drum member,
 2. braking meansoffering frictional resistance to and mounted about said drum member, 3.means for supporting said braking means about said drum and beingsecured to the first end of said apparatus,
 4. a radial-and-thrustbearing coupling disposed at and secured to the second end of saidapparatus, said drum being operatively connected thereto,
 5. arecirculating ball bearing assembly disposed within and secured to saiddrum,
 6. a screw member being fixed to the first end of said apparatus,said assembly and drum being capable of rotating and translatingthereon, and
 7. means for frictionally engaging and releasing saidbraking means to and from said drum, whereby as an axial load is imposedon said apparatus, it is transmitted to said braking means, drum andassembly, the energy of any load thereon in recess of a predeterminedfrictional value, at which value said assembly and drum rotate andtranslate one said screw member, being absorbed by heat generatedbetween said braking means and drum as the apparatus telescopes, withoutseparation of or damage or inoperativeness to said apparatus occuring.2. braking means offering frictional resistance to and mounted aboutsaid drum member,
 2. In the apparatus of claim 1, the addition of meansfor adjusting the tension of said braking means about said drum.
 2. anelongated drum member,
 3. braking means offering frictional resistanceto and mounted about said drum member,
 3. In the apparatus of claim 2including means for stopping rotation of said drum after said apparatushas telescoped.
 3. means for supporting said braking means about saiddrum and being secured to the first end of said apparatus,
 4. aradial-and-thrust bearing coupling disposed at and secured to the secondend of said apparatus, said drum being operatively connected thereto, 4.In the apparatus of claim 3, said stopping means comprising at least onediverging tapered surface mounted on said drum, said diverging taperedsurface cooperating with said braking means to stop rotation of saiddrum.
 4. means for supporting said braking means about said drum andbeing secured to one of such ends of said apparatus,
 5. aradial-and-thrust bearing coupling disposed at and secured to the otherof such ends of said apparatus, said drum being operatively connectedthereto,
 5. An apparatus for towing comprising in combination,
 5. arecirculating ball bearing assembly disposed within and secured to saiddrum,
 6. a screw member being fixed to the first end of said apparatus,said assembly and drum being capable of rotating and translatingthereon, and
 6. a recirculating ball bearing assembly disposed withinand secured to said drum,
 6. The apparatus of claim 5 including meansfor adjusting the tension of said braking means about said drum.
 7. Theapparatus of claim 6 including means for stopping rotation of said drumafter said apparatus has telescoped.
 7. a screw member being fixed toone of such ends of said apparatus, said assembly and drum being capableof rotating and translating thereon, and
 7. means for frictionallyengaging and releasing said braking means to and from said drum, wherebyas an axial load is imposed on said apparatus, it is transmitted to saidbraking means, drum and assembly, the energy of any load thereon inrecess of a predetermined frictional value, at which value said assemblyand drum rotate and translate one said screw member, being absorbed byheat generated between said braking means and drum as the apparatustelescopes, without separation of or damage or inoperativeness to saidapparatus occuring.
 8. The apparatus of claim 7 in which said stoppingmeans comprises at least one diverging tapered surface mounted on saiddrum, said diverging tapered surface cooperating with said braking meansto stop rotation of said drum.
 8. means for frictionally engaging andreleasing said braking means to and from said drum, whereby as an axialload is imposed on said apparatus, it is transmitted to said brakingmeans, drum and assembly, the energy of any load thereon in excess of apredetermined frictional value, at which value said assembly and drumrotate and translate on said screw member, being absorbed by heatgenerated between said braking means and drum as the apparatustelescopes, without separation of or damage or inoperativeness to saidapparatus occuring.